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Colorectal Cancer Health Center

Which Colon Screening Method is Safest?

Colonoscopy causes more perforations than sigmoidoscopy
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Feb. 4, 2003 -- Although the benefits of colorectal cancer screening far outweigh the risks for most people, new research shows that sigmoidoscopy procedures may be less likely to cause complications than the more extensive colonoscopy procedure.

The study, published in the Feb. 5 issue of the Journal of the National Cancer Institute, found that while the risk of damaging the colon wall during either procedure is very small, a sigmoidoscopy is only about half as likely to perforate or damage the colon wall as a colonoscopy.

A colonoscopy is a procedure that uses a small scope equipped with a camera inserted through the rectum to examine the entire length of the colon for abnormalities. Sigmoidoscopy uses a similar technique, but the scope only examines the section of the colon closest to the rectum.

Because it reaches a much smaller area of the colon, researchers say the less-expensive sigmoidoscopy is expected to have a lower incidence of perforation, but few studies have backed up that assumption.

In this study, researcher Nicolle M. Gatto, of the Mailman School of Public Health at Columbia University, and colleagues compared the risks of perforation of the colon associated with sigmoidoscopy and colonoscopy among people 65 and over who had undergone at least one of the procedures between 1991 and 1998.

Researchers found that 77 cases of perforation among the 39,286 colonoscopies studied compared to only 31 such cases among the 35,298 sigmoidoscopies studied. That translates to almost two perforations for every 1,000 colonoscopies performed and nearly one perforation for every 1,000 sigmoidoscopies. Of those who had perforations, the researchers noted that roughly 5% died within 14 days of the procedure.

Researchers say that the difference in risk between the two procedures has narrowed in recent years due to improvements in technology and training among doctors that perform the procedures, which have made both procedures -- especially colonoscopies -- safer.

Regular colorectal cancer screening is recommended for all adults once they reach age 50 and even earlier if they have a family history or other risk factors for the disease. Recent research suggests that colonoscopy is the most effective colorectal cancer screening method because it's the only one that looks at the entire colon. But it's also the most expensive and invasive procedure, which means other methods may be appropriate for some people or if colonoscopy is unavailable.

In fact, a national task force proposed new colorectal cancer screening guidelines this week that call for more extensive use of colonoscopy as the preferred screening method for most people.

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